[hpsdr] Penelope Power reading - failed under OpenHPSDR mRX-FFT v3.1.5

[Joe Martin K5SO]

Hi Georg, 

Could you be be caught in the "low power trap” that some people occasionally find when using Alex at low power with their PowerSDR Tx meter set for high power readings?  If you have Alex checked as being present the Tx power meter in PowerSDR gets its input from the Alex directional coupler, not directly from Penelope.  Keep in mind that the directional coupler on Alex is designed for a 100W signal level, so unless you have your Tx power meter set to its high sensitivity setting the values shown the PSDR Tx meter will have a 1 watt step and will not show sub-1-watt signals unless the meter is set to “high sensitivity”.  To check whether this is the issue set your Tx power meter in PSDR to high sensitivity and it will (should) show the Penelope output at sub-one-watt levels, even though it will still be using the 100W directional coupler in Alex, of course, so the accuracy of the coupler in that low range may or may not be all that great as less-than-a-watt signals are at the very low end of its range.  

73,  Joe K5SO


On Oct 16, 2013, at 10:29 AM, georg Prinz wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hello all hpsdr experimenters,
> 
> after long time, I try to setup my Penelope Transmitter with following environment:
> 
> - Win7
> - PowerSDR OpenHPSDR mRX-FFT v3.1.5(6/23/13)
> - Metis: 2.6
> - Mercury: 3.4
> - Penelope: 1.8
> - In Setup Menu/ Transmit the Tune Power is set to 100.
> - Drive slider in PowerSDR is set to 100.
> 
> Unfortunately I can't get any FWPwr reading in PowerSDR. It always shows 0 Watts.
> Tracking down the problem I am measuring on Penelope board (It is the end of the 3-wire cable comming from Mercury power indicator through connector) Plug P4,pin1 FwdPwr = 0.013V in receive mode and 0,168V when pressing TUN. The real power at ANT1  on Alex is 28dBm=631mW.
> RVPwr on P4 pin 2 is 0.003V.
> In the documentation it is said that the TX meter shall show power from 0.1W up to 100W.
> SWR shows always 1.0:1.
> 
> I can remember that my old PowerSDR software had no problems with the TX meter. At the moment I cannot check the old version anymore as all my firmware is updated to newest versions.
> 
> Does anyone have an idea how to proceed?
> 
> 73, Georg, dl2kp
> 


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